Thomas b



(No Model.)

T. B. "CHASE.

ELLIPTIO SPRING.

3 5 968 Patented July 5, 1887.

ala L UNITED STATES P TENT tries.

THOMAS E. CHASE, OF NEW YORK, N. Y., ASSIGNOR OF ONE-HALF TO. ELISHA R. W'HEELOOK, OF SAME PLACE.

ELLIPTIC SPRING.

SPECIFICATION forming part of Letters Patent No. 365,968, dated July 5,1887. Application filed September 2, 1886. Serial No. 212,522. (No model.)

spring of uniform resiliency throughout its length, so far as possible, and to decrease the weight of metal in the construction ofa spring of a given force. I

The invention consists in a method of increasing the resiliency of the plates on the ordinary elliptic spring, and in a method of increasing the resiliency of such improved elliptic spring by adding thereto an interme diate spiral spring, or its equivalent, as will be hereinafter more fully explained.

I have discovered, in the first place, that the resiliency of a leaf of an elliptic spring may be very greatly increased by forming the same into what I call a double-ogee shapethat is, a shape in which the section of the sprmg represents three alternatelyreversed curves. By building up my spring of such leaves I both increase the resisting force of the spring and distribute its elasticity more uniformly throughout the entire length. The structure likewise occasions a more uniform interlocking of the leaves throughout their lengths, which is advantageous in the resultingstructure. I likewise re-enforce my improved elliptic spring by a second spring, tending to draw together the exterior ends of the leaves. This structure will be readily understood from the accompanying drawings, in which- Figure 1 represents a view of my improved spring without the intermediate auxiliary spring; Fig. 2, a view of my completed spring with the auxiliary spring attached; Fig. 3, a view of a single leaf of my improved spring; Fig. 4., a cross-section of the same; Fig. 5, a view of the method of connecting the ends of the longer elliptic leaves.

In my drawings similar letters refer to similar parts.

A represents generally the leaves of my improved elliptic spring, which, as shown, are

I this is not essential.

held together at their centers by clamps B. The leaves of these springs are of the shape shown clearly in Figs. 3 and 4, forming, generally, three alternatel y-reversed curves, which I prefer to be curves of equal diameter, though When these leaves are laid one upon the other, they will interlock and make a spring, the structure of which insures great firmness. The principal object, however, is to insure a greater resisting force than is the case in a flat spring. The external ends of the single leaves may be attached together in any well-known way in the form of spring without the intermediate auxiliary spiral spring. In that form of spring, however, I prefer the form shown in the drawings.

F represents an intermediate spiral spring adapted to be compressed by the movement of the tension-rods G O, which rods are provided at their inner ends with offsets G, or similar contrivances, to bear against the ends of the spiral spring F. The external threaded ends of the tension-rods O O are provided with nuts E, which nuts are preferably concave on their inner surfaces, as shown in Fig. 5. The tension-rods pass through slots in the ends of the elliptic leaves A A, which slots are preferably vertically extended, so as to allow freedom of motion without cramping the ends of the tension-rods, which otherwise are liable to be cut off. The nuts E permit of the proper adjustment of the tension of the spiral spring F, and when adjusted their inner concave form prevents their turning and serves the purpose of a lock-nut there. Instead of the spiral spring F, I may use other forms of spring; but I prefer a compression spiral spring in that position. By reason of the combination of the corrugated elliptic spring with the inter nal spiral spring, I both secure greater resist ing force in the elliptic spring and also greater longitudinal rigidity in the leaves, which is important in the operation of the spring, with a corresponding decrease of weight.

The operation is as follows: Pressure applied in the ordinary way to the leaves of the elliptic spring tends both to straighten those leaves, and also, by reason of the separation of the ends, to compress the auxiliary spiral spring.

- I am aware that leaves of elliptic springs have been constructed of sections other than planes; but such forms have invariably proved unsatisfactory. By reason of the peculiar shape here shown, I obtain the greatest possible resisting force combined with uniform elasticity, and at the same time a greater longitudinal rigidity.

I do not limit myself to the particular method of holding, the leaves of the spring together by clamps, nor to the particular method of attaching the ends of the spring together.

Though Iprefer to have all the leaves of the spring corrugated, as described, yet my invention may be partly utilized by corrugating only one or more of the said leaves.

It is obvious that the peculiar longitudinal corrugations of my elliptic spring act in combination with theintermediat-e spiral spring by increasing the longitudinal rigidity of the leaves of the elliptic spring.

What I claim as my invention, and desire to secure by Letters Patent, is-

1. The combination of the parts A A of an elliptic spring,having hooked ends and oblong slots therein, nuts E, tension-rods G, and spring F, substantially as described.

2. The combination of leaves A A of an elliptic spring, having hookcd'ends and oblong slots therein, with tension-rods O 0, spring F, 0 and nuts E, having concave inner surfaces, substantially as described.

3. The combination of an elliptic spring,a1eaf or leaves of which is or are composed of a plate or plates longitudinally corru gated in the form 5 of three reversed curves,with an auxiliary 1ongitudinally-expanding spring connected to the united ends of the upper and lower parts of the elliptic spring by means of tension-rods, substantially as described.

4. The combination, with the upper and lower parts ofan elliptic spring, aleaforleaves of which is or are composed of a plate or plates longitudinally corrugated throughout their length in the form of three reversed curves, of 4 5 a spiral spring connected by two tension-rods to the points of union of the upper and lower parts of the elliptic spring, said rods overlapping each other at their inner ends, and each passing centrally through the spiral spring, 0 substantially as described.

In testimony whereof I have signed my. name to this specification in the presence of two subscribing witnesses.

THOS. B. CHASE.

Witnesses:

H. COUTANT, WM. A. POLLOCK. 

